Thermodynamic behavior of poly(cyclohexylethylene) in polyolefin diblock copolymers

We report the temperature dependence of the Flory-Huggins interaction parameter for three symmetric diblock copolymer systems containing poly(cyclohexylethylene) (PCHE): poly(cyclohexylethylene-b-ethylene) (CE), poly(cyclohexylethylene-b-ethylethylene) (CEE), and poly(cyclohexylethylene-b-ethylenepropylene) (CP). Order-disorder transition temperatures (T-ODT) were determined using dynamic mechanical spectroscopy and interpreted with mean-field theory, (chiN)(ODT) = 10.5, leading to well-defined expressions for chi(T) These results have been analyzed in the context of solubility parameter (6) theory resulting in a unique parameter delta(C) that describes the interactions in CE, CP, and CEE, where delta(C) < delta(EE), < delta(P) < delta(E) with (delta(E) - delta(C)) approximate to 1.6 MPa1/2 at 500 K. In contrast to the predictions of group contribution theory, this indicates that delta(C) is in surprisingly close proximity to the solubility parameter for poly(dimethylsiloxane).